southtarnation
Well Known Member
I know there are some thorp guys running lyc 320's with no scoop in the cowl, my question is are there any 4s or other rv's running no intake scoop?
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Scoopless cowl
- Thread starter southtarnation
- Start date
Wesael
Well Known Member
The -7 and -8 both have the option directly from van.
It utlizes a fiberglass intake duct that brings filtered air in from the left engine cooling air inlet ramp.
Pros: Look nice (IMHO)
Cons: Slower (there is a greater pressure drop by directing the air from the ramp to the air intake via the duct work. The engine will make less power with this set up.
I have flow both types. Everyone seems to comment about how good they look without the "scoop".
Having the need for speed steers me to getting over the looks thing
It utlizes a fiberglass intake duct that brings filtered air in from the left engine cooling air inlet ramp.
Pros: Look nice (IMHO)
Cons: Slower (there is a greater pressure drop by directing the air from the ramp to the air intake via the duct work. The engine will make less power with this set up.
I have flow both types. Everyone seems to comment about how good they look without the "scoop".
Having the need for speed steers me to getting over the looks thing
southtarnation
Well Known Member
Could the power loss from the pressure drop be equal or less to the aerodynamic gains rendering the same speeds with less hp more efficiently do you think?
It would matter at what altitude most of the flying would be done at correct?
At a higher alt the loss of power from the pressure drop would be greater? So maybe only at sea level would the trade off be comparable...
It would matter at what altitude most of the flying would be done at correct?
At a higher alt the loss of power from the pressure drop would be greater? So maybe only at sea level would the trade off be comparable...
The subject is a 320? Probably an updraft carb, so RV-7 or 8 horizontal induction ductwork isn't directly applicable. And it might be difficult to duplicate the RV-7-8 duct due to the shape of the RV-4 cowl.
I have heard of RV-4 builders happily ducting to the carb from a port in the rear baffle wall. There will probably be an air temperature rise between the cowl intake and the duct intake, which would result in a small HP loss. I've measured 15-16 degrees F in some personal experiments, but the parallel valve 320 may not heat it so much. On the plus side, conversion of dynamic to static should be good (MP gain), the cowl would be easy to R&R, fabrication would be simple, and you would eliminate the form drag of a pitot-type inlet.
I have heard of RV-4 builders happily ducting to the carb from a port in the rear baffle wall. There will probably be an air temperature rise between the cowl intake and the duct intake, which would result in a small HP loss. I've measured 15-16 degrees F in some personal experiments, but the parallel valve 320 may not heat it so much. On the plus side, conversion of dynamic to static should be good (MP gain), the cowl would be easy to R&R, fabrication would be simple, and you would eliminate the form drag of a pitot-type inlet.
southtarnation
Well Known Member
Yes, a 320 updraft. Switching to SJ cowl and plenum and was thinking of ducting air off the back of the baffle... Seems like the intake delete would be worth a couple of knots?
